I think there should be plastic bags using a plastic which dissolves in contact with saliva, but not in contact with water.

This should be eminently doable; we have a pretty good idea which enzymes human saliva contains.

Some number of kids suffocate every year because a bag gets stuck over their mouth and they can’t breathe. If the saliva that presumably gets on the bag from being over a kid’s open mouth broke the seal, even a little, they would be fine.

Comments

This is an interesting idea, but I doubt it would really work. I see two problems.

One is that those kind of bags would be very expensive. People would still use normal plastic bags, and shops wouldn't give these special plastic bags for free either. They might even be more expensive than bags made of textile or paper.

The other is that if these existed, the novelty value would make children actually want to try them and play with plastic bags. That might even increase the number of accidents.